Ownership is a key aspect of large-scale software development. We examine the
relationship between different ownership measures and software faults/failures in
three large software projects drawn from different process domains: Windows
Vista, the Eclipse Java IDE, and the Firefox Web Browser. We find that in all
cases, measures of ownership such as the number of low-expertise developers, and
the proportion of ownership for the top owner have a relationship with both
pre-release faults and post-release failures. However, we find that the strength
of the effects is related to the development process used. Vista shows the
strongest relationship with ownership level, followed by Eclipse, and then
Firefox, suggesting that the more that a project uses an open source style
process, the more that team sizes rather than ownership levels affect to
failures. We also find reasons that low-expertise developers make changes to
components and show that the removal of low-expertise contributions dramatically
decreases the performance of contribution based defect prediction. Finally we
provide recommendations for source code change policies and utilization of
resources such as code inspections based on our results.